Background: Psychological stress has long been linked with the exacerbation/onset of psoriasis.

Objectives: To determine if antecedent psychological stress is associated with the exacerbation/onset of psoriasis.

Methods: A search of the PubMed, PsycINFO, Cochrane library and ClinicalTrials.gov databases was performed. Surveys evaluating beliefs about stress reactivity were analysed separately. Suitable studies were meta-analysed.

Results: Thirty-nine studies (32 537 patients) were included: 19 surveys, seven cross-sectional studies, 12 case-control studies and one cohort study. Forty-six per cent of patients believed their disease was stress reactive and 54% recalled preceding stressful events. Case-control studies evaluating stressful events rates prior to the exacerbation (n = 6) or onset (n = 6) of psoriasis varied in time lag to recollection (≤ 9 months to ≥ 5 years). Pooling five studies evaluating stressful events preceding onset of psoriasis gave an odds ratio (OR) of 3·4 [95% confidence interval (CI) 1·8-6·4; I² = 87%]; the only study evaluating a documented stress disorder diagnosis reported similar rates between patients and controls (OR 1·2, 95% CI 0·8-1·8). Four studies evaluating stressful events prior to psoriasis exacerbation reported comparable rates with controls, whereas two found more frequent/severe preceding events among patients with psoriasis. A small prospective cohort study reported a modest association between stress levels and exacerbation of psoriasis (r = 0·28, P < 0·05).

Conclusions: The association between preceding stress and exacerbation/onset of psoriasis is based primarily on retrospective studies with many limitations. No convincing evidence exists that preceding stress is strongly associated with exacerbation/onset of psoriasis.